Anna,

If you can provide protection for your plants from excess wind/heat/
cold you should be able to plant out immediately. If you will be
having overnight lows in the 40s, peppers and courgettes may not
appreciate that too much.

I am using the "tomato cages" you can buy - the 3 foot ones that taper
out at the top - as mini-cloches for my peppers. I have had overnight
lows in the 40s and my plants have been out a week. They are doing
well and look terrific. I stick the cage in over the plant and wrap
it with plastic - open at the top. Keeps the winds out, we had gusts
to 30 a few days ago, all day - old news for your location I'm sure.

Good luck!